Improvement in alarm apparatus for steam-boilers



im l JOSEPH KIRK.

Improvement in Alarm Aparatusfor Steamv Boilers.

n l 8 All 3 e .el

UNITED STATES PATENT QEEICE.

JOSEPH KIRK, OF LONDON, ENGLAND, ASSIGNOR TO GEORGE JORDAN FIRMN.

IMPROVEMENT IN ALARM APPARATUS FOR STEAM-BOILERS.

Specification forming part of Letters Patent No. 119,522, dated October3, 1871.

To all whom it may concer-u:

Be it known that I, J osEPH KIRK, of No. 1l Blossom street, in the cityof London, England,

'a subject of the Queen of Great Britain, have and in what manner thesame is to be performed to be particularly described and ascertained inand by the following,` statement thereof-that is to say:

This invention has for its object improvements in alarm apparatus forgiving warning when the pressure in a steam-boiler or vessel workin gunder pressure is too high or the water-level too low. The apparatusconsists of a vessel containing a liquid, such as mercury, which willexpand by heat without sensible evaporation. The vessel is closed at thetop by a valve, and on the mercury is a iioat, which, at a -certaintemperature to which the apparatus is adjusted, presses against theunder side of the valve. The vessel containing the mercury is inclosedin a jacket, to which the steam or water from the boiler is admitted. Atthe top of the jacket is also a valveseat and a valve. The two valvesare connected by a stem, and as they are of the same area they pressuresupon them balance each other. The valves are thus very easily lifted bythe iloat.

' v/Vhen the valves are closed the pressure in the mercury-chamber onthe under side of the valve does not exceed the pressure above the uppervalve. This is insured by forming a small passage through the stemconnecting the two valves. A whistle is fixed on the top of the jacketover the upper valve, and when steam passes this whistle sounds. As soonas the valve is slightly `lift`ed by the float the steam rushes into themerapparatus constructed according to my invention.

a a is a vessel of iron. It is partly filled with mercury, and there isa loat, b, on the surface of the mercury. The iioat maybe iron or othermaterial on which the mercury will not act; it

should, however, be heavier than water. The vessel a is closed at thetop by a valve, c, and the quantity of mercury is so adjusted that thefloat unseats the valve when the mercury is sufat the ltemperature ofsteam of the pressure at which the instrument is to act. For a low-wateralarm the adjustment is made to a temperature a little over 2120, ratherhigher for a high-pressure boiler than for a low pressure. d is a jacketsurrounding the mercury-vessel, and this case is `in connection with theboiler by a pipe on which is a stop-cock. For a pressure-alarm aconnection 1s made with the upper part of the boiler, so that the jacketis always filled with steam; and for a low-water alarm the connection ismade with the lower part of the boiler, so that the jacket only fillswith steam when the water `in the boiler is low. The pipe connecting theinstrument with the boiler should be sufficiently long to insure thatthe temperature of the water in the jacket shall be considerably underthe boiler-temperature. When steam enters the casing theboiler-temperature is at once communicated to the apparatus. The jacketd is closed .at the top by the valve c1, which is soldered or cept whenthe float acts upon them; but immediately they are started by the floatthe steam enters the mercury-chamber a, more rapidly than it can escapeby the perforation c3, and the pressure which thus accumulates in thischamber' forces up the valves until the passage is fully open for thesteam to pass to the whistle.

Having` thus described the nature of my said invention and the manner ofperformingthe same7 I would have it understood that I claiml. Thecombination of the equilibriumyalves with a mercurydioat or equivalentinstrument for starting them from their seats7 and a chamber in

